This invention relates to improved apparatus and methods for the treatment of prostate cancer. More particularly, the present invention provides a prostate visualization device having at least one deployable member suitable for imaging the bladder/prostate junction, and methods of use.
Excluding nonmelanoma skin cancers, prostate cancer is the most common cancer afflicting American men. The American Cancer Society estimates that over 180,000 new cases will be diagnosed in the U.S. in the year 2000 alone, and that nearly 32,000 people will die from the disease. Prostate cancer is second only to lung cancer as the leading cause of cancer death in men, accounting for roughly 11%.
Prostate cancer is defined as malignant tumor growth within the prostate gland. Its cause is unknown, although high dietary fat intake and increased testosterone levels are believed to be contributory factors. A letter scale (xe2x80x9cAxe2x80x9d through xe2x80x9cDxe2x80x9d), which accounts for the location of the cancer, is commonly used to classify the stage of disease. In Stage A, the tumor is not palpable but is detectable in microscopic biopsy. Stage B is characterized by a palpable tumor confined to the prostate. By Stage C, the tumor extends locally beyond the prostate with no distant metastasis. By Stage D, cancer has spread to the regional lymph nodes or has produced distant metastasis.
In the early stages, prostate cancer is most commonly treated by either prostate removal or by brachytherapy. More advanced cases are treated by hormonal manipulation or orchiectomy to reduce testosterone levels and curb spreading of the disease, by chemotherapy, or by external beam radiation therapy.
With regard to treatment of early stage prostate cancer, the state of the art has several drawbacks. Radical prostatectomy is often recommended for treatment of localized stage A and B prostate cancers. Under general or spinal anesthesia, an incision is made through a patient""s abdomen or perineal area, and the diseased prostate is removed. The procedure is lengthy, especially if a lymph node dissection is simultaneously performed, and requires a hospital stay of 2-5 days. Possible complications include impotence and urinary incontinence.
Internal radiation therapy or brachytherapy has recently been developed and holds great promise for the treatment of early stage prostate cancer. Radioactive pellets or seeds of, for example, iodine-125, palladium-103, or iridium-192, are deposited directly into the prostate through needle placement. U.S. Pat. No. 5,928,130 to Schmidt provides a slightly modified example of such a needle device. Imaging techniques, such as transrectal ultrasound, CT scans, or MRI, are used to accurately guide placement of the radioactive material. Advantageously, radiation from the brachytherapy seeds is administered directly to the prostate with less damage to surrounding tissues, delivering a substantially higher radiation dosage to the prostate than to the surrounding tissues, as compared to external beam radiation therapy. The procedure need only be performed once, and impotence and urinary incontinence complications are significantly reduced, as compared to prostate removal procedures.
The seeds, which are permanently implanted, give off radiation for weeks or months. Their presence causes little discomfort, and they remain in the prostate after decay of the radioactivity. For several weeks following needle insertion, patients may experience pain in the perineal area, and urine may have a red-brown discoloration.
Although, when performed correctly, brachytherapy may provide several benefits when compared to prostate removal and other techniques, current apparatus and methods for delivering the seeds to target locations within the prostate are somewhat crude and are subject to practitioner error. The current method of identifying the depth of needle insertion is by ultrasound imaging. The junction of the base of the prostate and the bladder provides a common reference plane for needle insertion. Identifying this critical reference xe2x80x9cbasexe2x80x9d plane is critical to proper needle and seed placement.
One previously known technique for imaging the base plane is to visualize the plane in either transverse or sagittal ultrasound imaging. Injection of contrast agent may facilitate imaging. A catheter, such as a standard Foley catheter, may be inserted into the patient""s urethra proximal of the junction. Contrast agent comprising aerated K-Y jelly and water, may then be injected through an end port of the catheter. The agent moves distally towards the patient""s bladder and is visible to an ultrasound probe, positioned in the patient""s rectum, thereby facilitating imaging.
Attempts have been made to improve Foley catheters, as well as to facilitate improved imaging within a body lumen. For example, U.S. Pat. No. 5,715,825 to Crowley provides an acoustic imaging catheter with an inflatable dilation balloon and an ultrasound transducer. However, while Crowley may provide improved imaging, the device is mechanically and electrically complex, and is therefore costly. U.S. Pat. No. 5,916,153 to Rhea, Jr. provides a multifunction, modified Foley catheter. The device described in that patent, however, does not improve on current junction imaging techniques.
In view of the drawbacks associated with previously-known methods and apparatus for bladder/prostate junction imaging, it would be desirable to provide methods and apparatus that overcome such drawbacks.
It further would be desirable to provide methods and apparatus that provide reliable imaging of the bladder/prostate junction.
It still further would be desirable to provide methods and apparatus that may be used in conjunction with standard brachytherapy apparatus.
In view of the foregoing, it is an object of the present invention to provide methods and apparatus for bladder/prostate junction imaging that overcome drawbacks associated with previously-known methods and apparatus.
It is also an object of the present invention to provide methods and apparatus that provide reliable imaging of the bladder/prostate junction.
It still further is an object to provide methods and apparatus that may be used in conjunction with standard brachytherapy apparatus.
These and other objects of the present invention are accomplished by providing methods and apparatus for bladder/prostate junction imaging comprising a catheter having at least one distally deployable member that engages and defines the proximal region of the bladder. The deployable member is preferably constructed from a shape memory material that forms a petal-shaped configuration upon deployment. The deployable member is deployed within the patient""s bladder, and may be retracted proximally to conform to the proximal wall of a patient""s bladder. Gas pockets may be provided around the deployable member to enhance visibility with an ultrasound probe. Additionally, echo-contrast agent may be injected to the region to facilitate reliable imaging.
In a preferred embodiment, the deployable member comprises a plurality of petal-shaped Nitinol wires affixed to the distal end of a plunger that is coupled to a multi-lumen catheter. The catheter may include a deployment lumen, a bladder drainage lumen, a contrast injection lumen, and a prostatic therapy lumen. The catheter is advanced through a patient""s urethra into the patient""s bladder. The deployable member is deployed by advancing the plunger distally within the deployment lumen. Upon deployment within the bladder, the plunger is proximally retracted until the deployable member engages the proximal wall of the bladder. Echo-contrast agent then may be injected into a space near the bladder/prostate junction. Ultrasonic imaging may then proceed, often with an ultrasound probe positioned in the patient""s rectum. Urine also may be emptied from the bladder via the bladder drainage lumen, and the patient""s prostate may be accessed via the prostatic therapy lumen.
The deployment lumen may be used in combination with any of the drainage, contrast, and prostatic therapy lumens. In alternative embodiments, one or more catheter lumens may be configured to serve more than one function. For example, a single lumen catheter having only one distal outlet port may be provided whereby one or more proximal ports are in communication with the outlet port via the single lumen. In this embodiment, the single lumen of the catheter allows for passage of the deployable member, fluid injection, fluid drainage and delivery of prostatic therapy devices or therapeutic agents.
Additionally, tubing may cover the deployable member to form gas pockets around the deployable member such that the gas enhances ultrasonic imaging of the bladder/prostate junction. The tubing may comprise a variety of shapes and sizes to facilitate imaging of the deployable member.
Methods of using the present invention are also provided.